Surface Defects on MBE-Grown GaAs

Abstract

The most common macroscopic defects in GaAs layers grown by MBE, i.e. oval defects, were studied. TEM observation shows that oval defects include stacking faults and that the crystalline quality is considerably inferior around these stacking faults. The successive optical microscopic observation of step-etched surfaces reveals that for an epitaxial layer with an oval defect density of more than 10⁴/cm², the majority of the oval defects originate in the epitaxial layer, while for an epitaxial layer with an oval defect density of less than 10³/cm², they originate at the interface between the epitaxial layer and the substrate. X-ray topography and observation of the dislocation etch pits clearly show that substrate dislocations are not responsible for the oval defects.